1. Field of the Invention
This invention relates to a new and unique method for the extraction and reclamation of perchlorethylene dry cleaning solvent from spent dry cleaner filter cartridges which utilize a layer of activated charcoal and paper filter media to perform the filtering function.
2. Description of the Prior Art
Dry cleaner filter cartridges are used in the commercial dry cleaning process for the purpose of filtering dirt and lint from the perchlorethylene cleaning solvent. As garments are cleaned in the solvent within a dry cleaning machine, the solvent is pumped through the dry cleaner filter cartridges to entrap unwanted sediments.
Dry cleaner filter cartridges are generally cylindrical in shape and consist of an inner hollow metal tube, surrounded by a layer of activated charcoal contained in a larger diameter perforated metal tube, surrounded in turn by accordian-pleated paper filter media, all of which are encased within round metal end plates, and generally, a perforated cylindrical steel housing. (Only one manufacturer of dry cleaner filter cartridges known to the applicant does not use the perforated steel housings as described above.)
The present invention applies to all dry cleaning filter cartridges or filter inserts, including the three diferent size filter cartridges commonly used in the dry cleaning industry, i.e., the standard size having dimensions 7 3/4 inches in diameter by 14 3/8 inches long; the jumbo size having dimensions 13 1/4 inches in diameter by 18 1/4 inches long; and, the "split" size having dimensions 13 1/4 inches in diameter by 9 1/8 inches long. Dependent upon the volume of garment cleaning capacity for which a dry cleaning machine is designed, the number of filter cartridges used varies from machine to machine.
The dry cleaner filter cartridges are removed from the dry cleaning machine, from time to time, and replaced with new dry cleaner filter cartridges when the amount of dirt and lint entrapped within the filter media has increased to the point that the flow of cleaning solvent through the filter is impeded. This "clean-out" time is determined by a pressure increase shown on a pressure gauge installed on the dry cleaner filter cartridge canister.
All spent dry cleaner filter cartridges, when removed from the dry cleaning machine, contain residual perchlorethylene cleaning solvent. Manufacturers of dry cleaner machines recommend the dry cleaner operator reduce the amount of residual perchlorethylene cleaning solvent in the dry cleaner filter cartridges by allowing the dry cleaner filter cartridges to drain for a period of at least twenty-four hours. It is observed, however, that in actual practice most dry cleaner operators reduce the suggested drain time period. As a result, it has been discovered by test that the residual perchlorethylene cleaning solvent contained in dry cleaner filter cartridges selected at random from various dry cleaner operators varies on the average as follows:
______________________________________ Perchlorethylene Cleaning Solvent Residual in Discarded Filter Cartridge Size Dry Cleaner Filter Cartridges ______________________________________ 73/4 " diameter by 143/8 " 0.5 to 1.5 gallons long "standard" size 131/4 " diameter by 181/4 " 2.0 to 4.0 gallons long "jumbo" size 131/4 " diameter by 91/8 " 1.0 to 2.0 gallons long "split" size ______________________________________
Perchlorethylene cleaning solvent is identified as a toxic hazardous material by both federal (see the United States Environmental Protection Agency Resource Conservation and Recovery Act, 40 CFR, .0.250-265) and many state authorities (see, for example, California Health & Safety Code Annotated Chapters 6.5 and 13).
Generally, environmental disposal regulations require that after a hazardous material such as perchlorethylene cleaning solvent is used, it is considered to be a toxic hazardous waste material and must either be destroyed in a manner which will not leave any toxic hazardous waste material residues or else disposed of in a Class I landfill, which is required to have by law an impervious underlining to prevent the toxic hazardous waste material from percolating downward to contaminate an aquifer or the surrounding environment itself.
Examples of dangers caused by failure to properly dispose of toxic hazardous waste materials are seen in the national tragedies such as Stringfellow Chemical Pits in California, Love Canal in New York, or, Times Beach in Missouri where the full extent of damage to the ecosystem as well as to present and future generations of the nearby populace is still to be determined.
With these national tragedies still fresh in our minds, it is frightening to note the common method of disposal of spent perchlorethylene-laden dry cleaner filter cartridges throughout most of the United States is for the dry cleaner operator to illegally discard the dry cleaner filter cartridges with his common trash which is disposed of in Class II or Class III sanitary landfills.
Since landfills of these classes are not required to have impervious underlinings, contamination of aquifers and the environment from toxic hazardous perchlorethylene waste is possible. At the present time, only within certain areas of the State of California are dry cleaner operators forced, under penalty of fine, to enroll with a hazardous waste disposal service for the legal disposal of perchlorethylene-laden dry cleaner wastes.
It can be seen, then, that the extraction and reclamation of perchlorethylene from spent dry cleaner filter cartridges is desirable for two reasons. The first is cost reduction. The extracted perchlorethylene can be recycled for reuse, thus eliminating the need to purchase new replacement dry cleaning solvent.
The second reason is environmental. Although present legal codes allow for the disposal of perchlorethylene-laden wastes in Class I landfills, several states including Minnesota, Massachusetts and Pennsylvania, are considering legislation to prevent future land disposal of any perchlorethylene-laden wastes. Other states, including, California, have enacted legislation that restricts the level of concentration of perchlorethylene in wastes to be disposed of at any landfill to a maximum concentration of no more than 0.1% by weight.
Over the years, several methods have been used to extract perchlorethylene from dry cleaner filter cartridges. The first uses a drying cabinet with a vent connected to a carbon adsorption system. Dry cleaner filter cartridges are removed from the dry cleaning machine and placed within the drying cabinet where room air is drawn into the cabinet and around the cartridges. The perchlorethylene cleaning solvent is extracted from the solvent-laden air as it is passed through the carbon adsorption system.
The next method is similar to the above, except the dry cleaner filter cartridges are not removed from the dry cleaning machine for processing. The dry cleaner filter cartridges are left within the canister of the dry cleaning machine and room air is drawn into the canister and around and through the cartridges. As above, the perchlorethylene cleaning solvent is extracted from the solvent-laden air as it is passed through an external carbon adsorption system.
Also in use is a hot air recirculating system, wherein the dry cleaner filter cartridges are left within the canisters of the dry cleaning machines. Hot air, heated by an external source, is forced through the canisters holding the dry cleaner filter cartridges. The perchlorethylene cleaning solvent is extracted from the solvent-laden air as it is passed through an external water-cooled condenser or carbon adsorption system.
The final method to be described employs live steam injection wherein the dry cleaner filter cartridges are left within the canister of the dry cleaning machine. The canister is tightly sealed and, live steam is injected into the canister to maintain a pressure within the canister of 1.75 to 3.0 pounds per square inch. The resulting perchlorethylene vapor is passed through a pipe connected to an external water-cooled condenser and condensed and collected.
The above-described methods outline the state of the art developments in the art of perchlorethylene reclamation from dry cleaner filter cartridges since 1971 when efforts were first instituted to extract and reclaim perchlorethylene dry cleaning solvent from dry cleaner filter cartridges. Each of the above-described methods is time consuming, for example, a period of four and three-quarter hours for the steam injection method to twenty-four to forty-eight hours for the other methods is suggested to effectively extract the perchlorethylene cleaning solvent from the dry cleaner filter cartridges. None of the manufacturers of the equipment used in the above methods claim all perchlorethylene solvent is removed from the dry cleaner filter cartridges following the processing. All of the methods require the processed dry cleaner cartridges be discarded in a landfill following processing, which shall be illegal if and when, laws are enacted requiring zero hazardous material content for landfill disposal. All of the above-described methods process the dry cleaner filter cartridges in their assembled configuration as opposed to the disjoined configuration taught herein.